IPRangeExplorer

231.9.40.0/21

Multicast RFC 5771

Class D (Multicast) — /21 prefix — 2,046 usable hosts

Network Address
231.9.40.0
Broadcast Address
231.9.47.255
Subnet Mask
255.255.248.0
Usable Hosts
2,046
First Usable IP
231.9.40.1
Last Usable IP
231.9.47.254
Total IPs
2,048
Prefix Length
/21

Network address — the base address of the block (231.9.40.0). All devices in this subnet share this prefix. Cannot be assigned to a host.

Broadcast address — packets sent to 231.9.47.255 are delivered to every device in the subnet. Also reserved — not assignable.

Usable hosts — the 2,046 addresses between those two that you can assign to servers, VMs, or interfaces.

Subnet mask — 255.255.248.0 is the dotted-decimal equivalent of /21. Older tools and Cisco configs use this format instead of CIDR slash notation.

Full Details

CIDR Notation 231.9.40.0/21
Network Address 231.9.40.0
Broadcast Address 231.9.47.255
Subnet Mask 255.255.248.0
Wildcard Mask 0.0.7.255
Prefix Length /21
IP Address Class Class D (Multicast)
Total IP Addresses 2,048
Usable Host Addresses 2,046
First Usable IP 231.9.40.1
Last Usable IP 231.9.47.254
Network (Hex) 0xE7092800
Broadcast (Hex) 0xE7092FFF
Governing RFC RFC 5771
Address Type Multicast

Binary Representation

Network Address
11100111.00001001 11100111.00001001.00101000.00000000
Subnet Mask
11111111.11111111.11111000.00000000

The first 21 bits (1s in the mask) identify the network. The remaining 11 bits identify hosts within the network.

Split into Equal Subnets

Split 231.9.40.0/21 into 2 equal /22 subnets (1,022 usable hosts each).

# CIDR Network First Usable Last Usable Broadcast Hosts
1 231.9.40.0/22 231.9.40.0 231.9.40.1 231.9.43.254 231.9.43.255 1,022
2 231.9.44.0/22 231.9.44.0 231.9.44.1 231.9.47.254 231.9.47.255 1,022

/21 Subnet Reference

Total IPs 2,048
Usable Hosts 2,046
Subnet Mask 255.255.248.0
Wildcard 0.0.7.255
Full /21 reference →

Related Ranges

Parent /20 block 231.9.32.0/20 Sibling /21 block 231.9.32.0/21

Adjacent Prefix Sizes

/19 8,190 hosts /20 4,094 hosts /21 2,046 hosts /22 1,022 hosts /23 510 hosts

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